U.S. patent number 8,527,131 [Application Number 13/392,910] was granted by the patent office on 2013-09-03 for method for operating a drivetrain.
This patent grant is currently assigned to ZF Friedrichshafen AG. The grantee listed for this patent is Notker Amann, Alexander Banerjee. Invention is credited to Notker Amann, Alexander Banerjee.
United States Patent |
8,527,131 |
Banerjee , et al. |
September 3, 2013 |
Method for operating a drivetrain
Abstract
A method of operating a drive-train of a motor vehicle having a
hybrid drive with an internal combustion engine and an electric
machine, an electrical energy accumulator that can be charged when
the electric machine operates as a generator and discharged when
the electric machine operates as a motor, a transmission connected
between the hybrid drive and a drive output, and at least one
auxiliary power takeoff on either the transmission or the hybrid
drive side such that the auxiliary power takeoff can be operated
with variable energy demand within functional capability limits
that depend on the auxiliary power takeoff. Depending on the
current operating status of the hybrid drive unit, the electrical
energy accumulator and/or the auxiliary power takeoff, energy
available in the drive-train, but not required at the drive output,
can bypass the electrical energy accumulator and be stored in the
auxiliary power takeoff.
Inventors: |
Banerjee; Alexander
(Oberteuringen, DE), Amann; Notker (Friedrichshafen,
DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Banerjee; Alexander
Amann; Notker |
Oberteuringen
Friedrichshafen |
N/A
N/A |
DE
DE |
|
|
Assignee: |
ZF Friedrichshafen AG
(Friedrichshafen, DE)
|
Family
ID: |
43018957 |
Appl.
No.: |
13/392,910 |
Filed: |
August 31, 2010 |
PCT
Filed: |
August 31, 2010 |
PCT No.: |
PCT/EP2010/062701 |
371(c)(1),(2),(4) Date: |
February 28, 2012 |
PCT
Pub. No.: |
WO2011/026832 |
PCT
Pub. Date: |
March 10, 2011 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20120158232 A1 |
Jun 21, 2012 |
|
Foreign Application Priority Data
|
|
|
|
|
Sep 2, 2009 [DE] |
|
|
10 2009 029 119 |
|
Current U.S.
Class: |
701/22; 74/11;
180/65.21 |
Current CPC
Class: |
B60W
10/10 (20130101); B60W 10/30 (20130101); B60K
25/00 (20130101); B60W 10/26 (20130101); B60W
30/1888 (20130101); B60Y 2400/15 (20130101); Y02T
10/62 (20130101); Y02T 10/6282 (20130101); Y02T
10/6208 (20130101); B60L 2240/34 (20130101); B60W
20/00 (20130101); Y02T 10/84 (20130101) |
Current International
Class: |
B60L
11/00 (20060101); B60K 6/20 (20071001); F16H
37/00 (20060101) |
Field of
Search: |
;701/22,29,34
;180/65.2,65.1-65.8 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
101 46 477 |
|
Feb 2003 |
|
DE |
|
10 2006 022 249 |
|
Nov 2007 |
|
DE |
|
10 2007 003 756 |
|
Jul 2008 |
|
DE |
|
2008-280178 |
|
Nov 2008 |
|
JP |
|
2004/000597 |
|
Dec 2003 |
|
WO |
|
2007/043953 |
|
Apr 2007 |
|
WO |
|
2008/100284 |
|
Aug 2008 |
|
WO |
|
Primary Examiner: Shafi; Muhammad
Attorney, Agent or Firm: Davis & Bujold, PLLC
Claims
The invention claimed is:
1. A method of operating a drive-train of a motor vehicle, the
drive-train comprising a drive aggregate having a hybrid drive unit
with an internal combustion engine and an electric machine, an
electrical energy accumulator that is chargable when the electric
machine of the hybrid drive unit operates as a generator and is
dischargable when the electric machine of the hybrid drive unit
operates as a motor, a transmission connected between the hybrid
drive unit and a drive output, and at least one auxiliary power
takeoff coupled to the drive aggregate such that the at least one
auxiliary power takeoff being operable with variable energy demand
within functional capability limits that depend on the at least one
auxiliary power takeoff, depending on at least one of a current
operating status of the hybrid drive unit, a current operating
status of the electrical energy accumulator and a current operating
status of the at least one auxiliary power takeoff, the method
comprising the steps of: balancing energy for the drive train as a
whole, via operation of an electric intermediate circuit, based
upon an efficiency of each of the internal combustion engine, the
electric machine, the electrical energy accumulator and the at
least one auxiliary power takeoff, and a storage capacity and
condition parameters of the energy accumulator and functional
capability limits of the at least one auxiliary power takeoff such
that the electric intermediate circuit at least one of: storing a
portion of energy not required at the drive output in the
electrical energy accumulator, and directing a portion of energy,
not required at the drive output, to bypass the electrical energy
accumulator and converting the portion of the energy, not required
at the drive output, and storing the converted energy in an
auxiliary power takeoff energy store to achieve an optimum overall
efficiency of the drive-train, and the at least one auxiliary power
takeoff is one of a heating and a cooling aggregate, and the energy
not needed at the drive output bypassing the electrical energy
accumulator and being used by the one of the heating and the
cooling aggregate for one of heating and cooling one of the
internal combustion engine and a passenger compartment to within
admissible temperature limits so as to utilize the energy, not
needed at the drive output, as thermal energy.
2. The method according to claim 1, further comprising the step of
the one of the heating and the cooling aggregate is a heating
aggregate that warms up the internal combustion engine, and the
energy not needed at the drive output bypassing the electrical
energy accumulator and being used by the heating aggregate for
warming up the internal combustion engine to within admissible
temperature limits so as to utilize the energy, not needed at the
drive output, as thermal energy for warming up the internal
combustion engine.
3. The method according to claim 1, further comprising the step of
the one of the heating and the cooling aggregate is an
air-conditioning unit that either warms up or cools down the
passenger compartment, the energy not needed at the drive output
bypassing the electrical energy accumulator and being used by the
air-conditioning unit for either warming up or cooling down the
passenger compartment to within admissible temperature limits so as
to utilize the energy, not needed at the drive output, in the
passenger compartment.
4. The method according to claim 1, further comprising the step of
the at least one auxiliary power takeoff is either a hydraulically
or a pneumatically actuated auxiliary power takeoff, and the energy
not needed at the drive output bypassing the electrical energy
accumulator and being used to increase a working pressure to within
admissible pressure limits in either a hydraulic reservoir or a
pneumatic reservoir.
5. A method of operating a drive-train of a motor vehicle, the
drive-train comprising a drive aggregate having a hybrid drive unit
with an internal combustion engine and an electric machine, an
electrical energy accumulator that is chargable when the electric
machine of the hybrid drive unit operates as a generator and is
dischargable when the electric machine of the hybrid drive unit
operates as a motor, a transmission connected between the hybrid
drive unit and a drive output, and at least one auxiliary power
takeoff on at least one of a transmission side and a drive
aggregate side such that the at least one auxiliary power takeoff
operable with variable energy demand within functional capability
limits that depend on the at least one auxiliary power takeoff,
depending on at least one of a current operating status of the
hybrid drive unit, a current operating status of the electrical
energy accumulator and a current operating status of the at least
one auxiliary power takeoff, the method comprising the steps of:
balancing energy for the drive train as a whole, via operation of
an electric intermediate circuit, based upon an efficiency of each
of the internal combustion engine, the electric machine, the
electrical energy accumulator and the at least one auxiliary power
takeoff, and a storage capacity and condition parameters of the
energy accumulator and functional capability limits of the at least
one auxiliary power takeoff such that the electric intermediate
circuit at least one of: storing a portion of energy not required
at the drive output in the electrical energy accumulator, and
directing a portion of energy, not required at the drive output, to
bypass the electrical energy accumulator and converting the portion
of the energy, not required at the drive output, and storing the
converted energy in an auxiliary power takeoff energy store to
achieve an optimum overall efficiency of the drive-train, and the
at least one auxiliary power takeoff being a cooling aggregate that
cools a refrigeration chamber, and the energy not needed at the
drive output bypassing the electrical energy accumulator and being
used by the cooling aggregate for cooling down the refrigeration
chamber to within admissible temperature limits so as to store the
energy, not needed at the drive output, as thermal energy in the
refrigeration chamber.
6. A method of operating a drive-train of a motor vehicle, the
drive-train comprising a drive aggregate having a hybrid drive unit
with an internal combustion engine and an electric machine, an
electrical energy accumulator that is chargable when the electric
machine of the hybrid drive unit operates as a generator and is
dischargable when the electric machine of the hybrid drive unit
operates as a motor, a transmission connected between the hybrid
drive unit and a drive output, and at least one auxiliary power
takeoff on at least one of a transmission side and a drive
aggregate side such that the at least one auxiliary power takeoff
operable with variable energy demand within functional capability
limits that depend on the at least one auxiliary power takeoff,
depending on at least one of a current operating status of the
hybrid drive unit, a current operating status of the electrical
energy accumulator and a current operating status of the at least
one auxiliary power takeoff, the method comprising the steps of:
balancing energy for the drive train as a whole, via operation of
an electric intermediate circuit, based upon an efficiency of each
of the internal combustion engine, the electric machine, the
electrical energy accumulator and the at least one auxiliary power
takeoff, and a storage capacity and condition parameters of the
energy accumulator and functional capability limits of the at least
one auxiliary power takeoff such that the electric intermediate
circuit at least one of: storing a portion of energy not required
at the drive output in the electrical energy accumulator, and
directing a portion of energy, not required at the drive output, to
bypass the electrical energy accumulator and converting the portion
of the energy, not required at the drive output, and storing the
converted energy in an auxiliary power takeoff energy store to
achieve an optimum overall efficiency of the drive-train, and the
at least one auxiliary power takeoff being a cooling fan that cools
an internal combustion engine, and the energy not needed at the
drive output bypassing the electrical energy accumulator and being
used by the cooling fan for cooling the internal combustion engine
to within admissible temperature limits so as to utilize the
energy, not needed at the drive output, as thermal energy for
cooling the internal combustion engine.
7. A method of operating a drive-train of a motor vehicle, the
drive-train comprising a drive aggregate having a hybrid drive unit
with an internal combustion engine and an electric machine, an
electrical energy accumulator that is chargable when the electric
machine of the hybrid drive unit operates as a generator and is
dischargable when the electric machine of the hybrid drive unit
operates as a motor, a transmission connected between the hybrid
drive unit and a drive output, and at least one auxiliary power
takeoff on at least one of a transmission side and a drive
aggregate side such that the at least one auxiliary power takeoff
operable with variable energy demand within functional capability
limits that depend on the at least one auxiliary power takeoff,
depending on at least one of a current operating status of the
hybrid drive unit, a current operating status of the electrical
energy accumulator and a current operating status of the at least
one auxiliary power takeoff, the method comprising the steps of:
balancing energy for the drive train as a whole, via operation of
an electric intermediate circuit, based upon an efficiency of each
of the internal combustion engine, the electric machine, the
electrical energy accumulator and the at least one auxiliary power
takeoff, and a storage capacity and condition parameters of the
energy accumulator and functional capability limits of the at least
one auxiliary power takeoff such that the electric intermediate
circuit at least one of: storing a portion of energy not required
at the drive output in the electrical energy accumulator, and
directing a portion of energy, not required at the drive output, to
bypass the electrical energy accumulator and converting the portion
of the energy, not required at the drive output, and storing the
converted energy in an auxiliary power takeoff energy store to
achieve an optimum overall efficiency of the drive-train; and
increasing a load operating point of the internal combustion engine
based of an energy balance.
8. The method according to claim 7, further comprising the step of,
at high driving speeds within the functional capability limits of
the at least one auxiliary power takeoff, preventing supply of
further energy to the at least one auxiliary power takeoff
concerned based on the energy balance.
9. A method for operating a drive-train of a motor vehicle, the
drive-train comprising a hybrid drive unit with an internal
combustion engine and an electric machine, an electrical energy
accumulator that is chargable when the electric machine operates as
a generator and dischargable when the electric machine operates as
a motor, a transmission that is connected between the hybrid drive
unit and a drive output, and at least one auxiliary power takeoff
connected to at least one of the transmission and the hybrid drive,
the at least one auxiliary power takeoff is operated with a
variable energy demand within functional capability limits that
depend on the at least one auxiliary power takeoff, depending on a
current operating status of at least one of the hybrid drive unit,
the electrical energy accumulator and the at least one auxiliary
power takeoff, the method comprising the steps of: balancing enemy
for the drive train as a whole, via operation of an electric
intermediate circuit, based upon at least one of an efficiency of
the internal combustion engine, an efficiency of the electric
machine, an efficiency of the electrical energy accumulator, an
efficiency of the at least one auxiliary power takeoff, and storage
capacity and condition parameters of the energy accumulator and
functional capability limits of the at least one auxiliary power
takeoff such that the electric intermediate circuit at least one
of: storing a portion of energy that is not required at the drive
output in the electrical energy accumulator, and directing a
portion of energy that is not required at the drive output to
bypass the electrical energy accumulator and converting and storing
the portion of the energy that is not required at the drive output
in an auxiliary power takeoff energy store; and the at least one
auxiliary power takeoff being either a hydraulically or a
pneumatically actuated auxiliary power takeoff, and the energy not
needed at the drive output bypassing the electrical energy
accumulator and being used to increase a working pressure to within
admissible pressure limits in either a hydraulic reservoir or a
pneumatic reservoir.
Description
This application is a National Stage completion of
PCT/EP2010/062701 filed Aug. 31, 2012, which claims priority from
German patent application serial no. 10 2009 029 119.9 filed Sep.
2, 2009.
FIELD OF THE INVENTION
The invention concerns a method for operating a drivetrain of a
motor vehicle.
BACKGROUND OF THE INVENTION
The main components of a drive-train are a drive aggregate and a
transmission. The transmission converts rotational speeds and
torques, and transmits a traction force provided by the drive
aggregate to a drive output of the drive-train. The present
invention concerns a method for operating a drive-train having a
drive aggregate in the form of a hybrid drive unit and at least one
auxiliary power takeoff on the transmission side or on the drive
aggregate side.
The hybrid drive unit of such a drive-train comprises an internal
combustion engine and an electric machine, the electric machine of
the hybrid drive unit can be operated as a generator or as a motor.
When the electric machine of the hybrid drive unit is operating as
a generator, an electrical energy accumulator of the drive-train is
predominantly charged, and when the electric machine of the hybrid
drive unit is operated as a motor the electrical energy accumulator
of the drive-train is predominantly discharged.
An auxiliary drive, also known as an auxiliary power takeoff (PTO),
draws power from the transmission side or from the drive aggregate
side, this power then not being available at the drive output as
traction force. An auxiliary power takeoff can be used, for
example, for a cooling aggregate of a refrigerator vehicle or for a
hydraulic press of a garbage disposal vehicle or for a
hydraulically operated crane of a utility vehicle, or the like.
Until now it has been difficult to operate a drive-train with a
hybrid drive unit and at least one auxiliary power takeoff in an
efficient manner.
SUMMARY OF THE INVENTION
Starting from there, the present invention addresses the problem of
providing a new type of method for operating a drive-train of a
motor vehicle.
According to the invention, depending on the current operating
status of the hybrid drive unit and/or depending on the current
operating status of the electrical energy accumulator and/or
depending on the current operating status of the auxiliary power
takeoff, energy available in the drive-train but not required as
traction force provided at the drive output bypasses the electrical
energy accumulator and is stored in the auxiliary power
takeoff.
The present invention makes possible the efficient operation of a
drive-train with a drive aggregate in the form of a hybrid drive
unit and with at least one auxiliary power takeoff. Depending on
the current operating status of the hybrid drive unit and/or
depending on the current operating status of the electrical energy
accumulator and/or depending on the current operating status of the
auxiliary power takeoff, energy or power available in the
drive-train but not required as traction force at the drive output
bypasses the electrical energy accumulator and is stored in the
auxiliary power takeoff.
The advantage of bypassing the electrical energy accumulator is
that the energy throughput through the same is smaller and the
electrical energy accumulator can therefore be operated in a more
protective manner. Furthermore, the storing of energy in the
auxiliary power takeoff increases the energy storage capacity of
the drive-train above and beyond the extent made possible by the
electrical energy accumulator alone. So to speak, this is
equivalent to a virtual enlargement of the storage capacity of the
electrical energy accumulator.
BRIEF DESCRIPTION OF THE DRAWINGS
An example embodiment of the invention, to which it is not limited,
is explained in more detail with reference to the drawing, which
shows:
FIG. 1: An example of a drive-train layout in a motor vehicle, with
which the method according to the invention can be used;
FIG. 1A: An example of a drive-train layout in a motor vehicle in
which both power takeoffs are electrically driven, and
FIG. 2: A block diagram showing the electrical flow of the
drive-train of FIG. 1A, to clarify the method according to the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention concerns a method for operating a drive-train
that comprises a hybrid drive unit and at least one auxiliary power
takeoff. In a very schematic manner FIG. 1 shows a drive-train
layout of a drive-train with which the method according to the
invention can be used. Thus, the drive-train shown in FIG. 1
comprises a hybrid drive unit with an internal combustion engine 1
and an electric machine 2, and with a transmission 4 connected
between the hybrid drive unit, namely its electric machine 2, and a
drive output 3 of the drive-train. In the example embodiment shown,
a clutch 5 can be connected between the internal combustion engine
1 and the electric machine 2. Also in the example embodiment shown,
a clutch 6 is connected between the electric machine 2 and the
transmission 4, such that the clutch 6 constitutes a starting
element which can even be a transmission-internal clutch.
The drive-train of FIG. 1 also has two auxiliary power takeoffs,
namely an auxiliary power takeoff 7 on the transmission side and an
auxiliary power takeoff 8 on the drive aggregate side. The
auxiliary power takeoff 7 on the transmission side draws power from
the transmission 4, which is then not available at the drive output
3 as traction force. The auxiliary power takeoff 8 on the drive
aggregate side draws power from the hybrid drive unit, namely from
the electric machine 2 thereof.
FIG. 2 shows another block diagram for the drive-train in FIG. 1A,
such that in FIG. 2, besides the assemblies already mentioned,
namely besides the internal combustion engine 1, the electric
machine 2 and the two auxiliary power takeoffs 7 and 8, energy
storage means are also shown. Thus, a fuel tank 9 of the
drive-train holds fuel which is converted by the internal
combustion engine 1 into kinetic energy of the motor vehicle, the
mass 10 of the motor vehicle storing the kinetic energy
thereof.
The kinetic energy of the vehicle's mass 10 can also be increased
by the electric machine 2 of the hybrid drive unit, and when this
is taking place the electric machine 2 predominantly discharges an
electrical energy accumulator 11 of the drive-train. As shown in
FIG. 2, between the electric machine 2 and the electrical energy
accumulator 11 there is connected an electric intermediate circuit
12, which is designed as a direct-current intermediate circuit. As
indicated by the arrows in FIG. 2, when the electric machine 2 is
operating as a generator some kinetic energy derived from the
vehicle's mass 10 can be converted into electrical energy for the
predominant charging of the electrical energy accumulator 11, and
the discharging and charging of the electrical energy accumulator
11 in each case take place by way of the electric intermediate
circuit 12.
FIG. 2 also shows details of the auxiliary power takeoff 7 on the
transmission side and of the auxiliary power takeoff 8 on the drive
aggregate side. As an example, let it be assumed that the auxiliary
power takeoff 7 on the transmission side is, for example, a
hydraulically actuated auxiliary power takeoff, this hydraulically
actuated auxiliary power takeoff 7 comprising an electrically
powered hydraulic pump 13 supplied with electrical energy by the
electric intermediate circuit 12, which can convert the electrical
energy into hydraulic energy that can be stored in a hydraulic
storage device 14 of the auxiliary power takeoff 7. The arrows in
FIG. 2 also show that, conversely, the hydraulic energy can be
converted into electrical energy.
The auxiliary power takeoff 8 on the drive aggregate side
comprises, for example, a cooling aggregate 15 supplied with
electrical energy by the electric intermediate circuit 12, the
cooling aggregate 15 cooling a refrigeration chamber 16 of the
drive-train, which also functions as a thermal energy store 16.
In the context of the present invention it is proposed to operate
such a drive-train in such manner that, depending on the current
operating status of the hybrid drive unit, namely depending on the
current operating status of the internal combustion engine 1 and
the electric machine 2 thereof, and/or depending on the current
operating status of the electrical energy accumulator 11 and/or
depending on the current operating status of the respective
auxiliary power takeoff aggregate 7 or 8, energy available in the
drive-train but not required in the form of traction force at the
drive output 3 bypasses the electrical energy accumulator 11 and is
stored in the auxiliary power takeoff 7 and/or 8.
Then, if as shown in FIG. 2 the auxiliary power takeoff 8 comprises
a cooling aggregate 15 that serves to cool the refrigeration
chamber 16, energy not required at the drive output 3 can bypass
the electrical energy accumulator 11 and can be used by the cooling
aggregate 15 for cooling the refrigeration chamber 16 to within
admissible temperature limits thereof, in order in that way to
store the energy not needed at the drive output in the
refrigeration chamber 16 as thermal energy. For example, the
refrigeration chamber can be operated without deterioration of its
functionality within a defined, admissible temperature range, so
that excess energy available in the drive-train but not required to
contribute to the traction force can be used, while bypassing the
electrical energy accumulator 11, to cool down the refrigeration
chamber to within the admissible temperature range more
effectively. The temperature limits are the functional capability
limits of the refrigeration chamber 16 or cooling aggregate 15.
In the case of the hydraulically actuated auxiliary power takeoff 7
energy not needed at the drive output can again bypass the
electrical energy accumulator 11 and be used, without functional
deterioration, to increase a working pressure to within admissible
pressure limits in the hydraulic storage device 14 of the auxiliary
power takeoff 7. The pressure limits are the functional capability
limits of the hydraulically actuated auxiliary power takeoff 7.
Likewise, if the auxiliary power takeoff 8 is a cooling fan that
serves to cool the internal combustion engine 1, energy not needed
at the drive output 3 can bypass the electrical energy accumulator
11 and be used by the cooling fan to cool down the internal
combustion engine 1 to within admissible temperature limits, so
that the energy not needed at the drive output 3 is used for
thermal purposes to cool the internal combustion engine, namely as
cooling power which is thermally stored in the mass of the internal
combustion engine 1.
If the auxiliary power takeoff 8 is a heating aggregate that serves
to warm up an internal combustion engine 1, energy not needed at
the drive output 3 can bypass the electrical energy accumulator 11
and be used by the heating aggregate to warm up the internal
combustion engine 1 to within admissible temperature limits, so
that the energy not needed at the drive output 3 is used for
thermal purposes to warm up the internal combustion engine, namely
as heating power which is thermally stored in the mass of the
internal combustion engine 1.
If the auxiliary power takeoff 8 is an air-conditioning unit that
serves to warm up or cool down a passenger compartment, energy not
needed at the drive output 3 can bypass the electrical energy
accumulator 11 and be used by the air-conditioning unit to warm or
cool the passenger compartment within admissible temperature
limits, so that the energy not needed at the drive output 3 is used
in the passenger compartment, namely stored thermally.
Accordingly, an insight of the present invention is that a
drive-train with a hybrid drive unit and an auxiliary power
takeoff, which can be operated with variable energy demand without
functional impairment within functional capability limits that
depend on the auxiliary power takeoff, can be operated efficiently
in that, depending on the operating status of the hybrid drive unit
and/or depending on the operating status of the electrical energy
accumulator and/or depending on the operating status of the
auxiliary power takeoff, energy not required at the drive output 3
as drive power can bypass the electrical energy accumulator 11 and
can be stored in an auxiliary power takeoff 7 and/or 8. In this way
the electrical energy accumulator 11 is operated in a more
protective manner since the energy passing through it is
reduced.
Furthermore, this results in a virtual enlargement of the storage
capacity of the electrical energy accumulator 11, since excess
energy not needed as drive power can be stored not only in the
electrical energy accumulator 11 itself, but also in energy storage
means of the auxiliary power takeoff aggregates 7 and/or 8. The
auxiliary power takeoff aggregates have variable power demand and
can be operated within admissible functional capability limits
without impairment of their function. The storage of the energy
that bypasses the electrical energy accumulator 11 in one or more
auxiliary power takeoff aggregate(s) takes place in this case,
having regard to and complying with the functional capability
limits specific to the auxiliary power takeoff aggregates.
According to an advantageous further development of the present
invention, depending on the current operating status of the hybrid
drive unit, namely depending on the current operating status of the
internal combustion engine 1 and of the electric machine 2, and/or
depending on the current operating status of the electrical energy
accumulator 11 and/or depending on the current operating status of
the auxiliary power takeoff or of each auxiliary power takeoff, an
energy balance covering the entire drive-train is determined.
On the basis of the energy balance, energy not required at the
drive output 3 is stored in the electrical energy accumulator 11
and/or, bypassing the electrical energy accumulator 11, it is
stored in the respective auxiliary power takeoff 7 and/or 8, so
ensuring an optimum overall efficiency of the drive-train. This
ensures high energy efficiency when the drive-train is operated,
which takes into account the efficiency of each individual
aggregate involved, i.e. that of the internal combustion engine 1
and the electric machine 2 and the electrical energy accumulator 11
and the auxiliary power takeoffs 7 and 8.
In determining the energy balance to ensure an optimal overall
efficiency of the drive-train, not only are the efficiencies of the
aggregates involved taken into account, but rather, also the
storage capacities and condition parameters of the respective
energy stores and the existing degrees of freedom and functional
capability limits of the respective auxiliary power takeoffs.
Preferably, energy is stored in whichever energy store can store
the currently available energy in the most efficient manner, as
viewed over the drive-train as a whole.
By virtue of the energy balance determined, to achieve optimum
overall efficiency of the drive-train it is possible, for example,
to increase a load operating point of the internal combustion
engine, namely if the energy balance shows that increasing the load
operating point of the internal combustion engine would increase
the overall efficiency of the drive-train.
When a load operating point is increased, excess energy supplied by
the internal combustion engine 1 can be used for charging the
various energy storage means present.
Furthermore, on the basis of the energy balance determined it is
possible, for example at high driving speeds of the drive-train, to
supply no additional energy to the auxiliary power takeoff, again
within admissible functional capability limits of the auxiliary
power takeoff concerned, in order thereby to intensify the
discharging of the energy store of the auxiliary power takeoff and
so to provide storage capacity in the energy store for the braking
energy to be expected at high driving speeds, which is transformed
into electrical energy by recuperation. In this way electrical
energy produced by recuperation, for example during braking, can
bypass the electrical energy accumulator 11 and be used, for
example by the auxiliary power takeoff 7 to increase the working
pressure in the hydraulic reservoir 14 by means of the hydraulic
pump 13, or by the auxiliary power takeoff 8 to lower the
temperature in the refrigeration chamber 16 by activating the
cooling aggregate 15. In this way, at high speeds the bypassing of
the electrical energy accumulator 11 can be planned for in
anticipation.
INDEXES
1 Internal combustion engine 2 Electric machine 3 Drive output 4
Transmission 5 Clutch 6 Clutch 7 Auxiliary power takeoff on the
transmission side 8 Auxiliary power takeoff on the drive aggregate
side 9 Fuel tank 10 Mass of the vehicle 11 Electrical energy
accumulator 12 Intermediate circuit 13 Hydraulic pump 14 Hydraulic
energy store 15 Cooling aggregate 16 Thermal energy store
* * * * *